the collection systems and shall be designed for minimum dead space.

(2) The design and installation of the necessary fittings shall not disturb the normal function of the fuel system components or the normal pressure relationships in the system.

(b) (1) Inspect the fuel system carefully to insure the absence of any leaks to the atmosphere of either liquid or vapor which might affect the accuracy of the test or the performance of the control system. Corrective action, if any, shall be reported with the test results under § 85.51.

(2) Care should be exercised, in the application of any pressure tests, neither to purge nor load the evaporative emission control system.

(c) Prepare fuel tank for recording the temperature of the prescribed test fuel at its approximate midvolume.

(d) Provide additional fittings and adapters, as required to accommodate a fuel drain at the lowest point possible in the tank as installed on the vehicle. § 85.73 Vehicle preconditioning (fuel evaporative emissions).

Test vehicles equipped with fuel evaporative emission control systems or devices subject to the provisions of this part shall be preconditioned as follows:

(a) The test vehicle will be operated under the conditions prescribed for mileage accumulation, § 85.91, for 1 hour immediately prior to the operations prescribed below.

(b) The fuel tank will be drained and specified test fuel (§ 85.71(a)) added. Care will be exercised against abnormal purging or loading of the evaporative emission control system or device as a result of draining or fueling the tank.

(c) The test vehicle will be placed on the dynamometer and operated through nine 7-mode cycles, according to the applicable requirements and procedures of §§ 85.75-85.80 except that the engine need not be cold when starting the run on the dynamometer. During the run the ambient temperature shall be between 68° F. and 86° F.

(d) The engine and cooling fan shall be stopped upon completion of the ninecycle dynamometer operation and the vehicle permitted to soak either on or off the dynamometer stand at an ambient temperature between 76° F. and 86° F.

for a period of not less than 1 hour prior to the soak period prescribed in § 85.74 (a) (1).

§ 85.74 Evaporative emission collection

procedure.

The standard test procedure consists of three parts described below which are to be performed in sequence and without any interruption in the test conditions prescribed.

(a) Diurnal breathing loss test. (1) The test vehicle will be allowed to "soak" in an area where the ambient temperature is maintained between 60° F. and 86° F. for a period of not less than 10 hours. (The vehicle preparation requirements of § 85.72 may be performed during this period.) It will then be transferred to a soak area where the ambient temperature is maintained between 76° F. and 86° F. Upon admittance to the 76° F.-86° F. soak area, the prescribed fuel tank thermocouple will be connected to the recorder and the fuel and ambient temperatures recorded at a chart speed of approximately 12 inches per hour (or equivalent record).

(2) The fuel tank of the prepared test vehicle, preconditioned according to § 85.73, will be drained and recharged with the specified test fuel, § 85.71 (a) to the prescribed "tank fuel volume," defined in § 85.1. The temperature of the fuel following the charge to the tank shall be 60° F.±2° F. Care should be exercised against abnormal loading of the evaporative emission control system or device as a result of fueling the tank.

(3) Immediately following the fuel charge to the tank, the exhaust pipe(s) and inlet pipe to the air cleaner will be plugged and the prescribed vapor collection systems installed on all fuel system external vents. Multiple vents may be connected to a single collection trap provided that, where there is more than one external vent on a fuel system distinguishing between carburetor and tank vapors, separate collection systems will be employed to trap the vapors from the separate sources. Every precaution will be taken to minimize the lengths of the collection tubing employed and to avoid sharp bends across the entire system.

(4) Artificial means will be employed to heat the fuel in the tank to 84° F. ±2° F. The prescribed temperature of the fuel shall be achieved over a period of

60 minutes

10 minutes using a constant rate of heat input. After a minimum of 1 hour, following admittance to the 76° F.-86° F. soak area, the vehicle will be moved onto the dynamometer stand for the subsequent part of the test. The fuel tank thermocouple may be temporarily disconnected to permit moving the test vehicle. Plugs will be removed from the exhaust pipe(s) and inlet pipe to the air cleaner.

(b) Running loss test. (1) The test vehicle will be placed on the dynamometer with the hood up and the cooling fan positioned between 8" and 12'' from the grill and directed squarely at the radiator. (Exception: air cooled engines). The ambient air temperature will be maintained between 68° F.-86° F. and recorded, together with the fuel temperature, at a chart speed of approximately 12 inches per hour (or equivalent record).

(2) Where the only external vent(s) is located in the immediate vicinity of the carburetor air horn, such that any “running loss" emissions would be inducted into the engine, there is no requirement to collect any vapor losses during this part of the test and the vapor-loss measurement system will be temporarily disconnected and clamped.

(3) The vehicle will be operated on the dynamometer according to the requirements and procedures of §§ 85.75-85.85. The engine and fan will be turned off upon completion of the dynamometer run and the exhaust and air cleaner inlet pipes will be replugged.

(4) Any vapor collection systems employed during this part of the test will be left intact for their continued use during the following part. Any part of the vapor collection system disconnected during this phase of the test will be reconnected for the following phase.

(c) Hot soak test. Upon completion of the dynamometer run, the test vehicle will be permitted to soak with hood down for a period of 1 hour at an ambient temperature between 76° F. and 86° F. This operation completes the test. The traps are disconnected and weighed according to § 85.82.

§ 85.75 Dynamometer operation cycle. (a) The following 7-mode cycle shall be followed in dynamometer operation tests.

(b) The following equipment will be used for dynamometer tests:

(1) Chassis dynamometer-equipped with power absorption unit and flywheels.

(2) Cooling fan-A fixed-speed fan will be used. It will have sufficient capacity to maintain engine cooling during sustained operation on the dynamometer and its air moving capacity shall not exceed 5,300 c.f.m.

§ 85.76 Dynamometer procedure.

(a) The vehicle shall be tested from a cold start. Four warmup cycles and five hot cycles make a complete dynamometer run. Exhaust emission measurements for hydrocarbons and carbon monoxide will be performed during the four warmup cycles and during the sixth and seventh (hot) cycles.

(b) Special considerations:

(1) On rolls less than 20 inches in diameter, the drive wheel tires will be inflated to 45 p.s.i.g. in order to prevent tire damage.

(2) The vehicle will be nearly level when tested in order to prevent fuel distribution unusual from that normally observed.

(3) The cooling fan will be positioned between 8 and 12 inches from the grill and directed squarely at the radiator (exception: air-cooled engines) and the dynamometer run will be made with hood up.

(4) Flywheels giving equivalent inertia as shown in the following table shall be used. Flywheels giving heavier inertia may be used provided that the specified "equivalent inertia weight" is used in the formula for determining "Exhaust Volume." (See § 85.87 (g) (4) (iii).)

shift speeds as indicated below (where possible; if not, cut into time of next mode). Shifting shall be accomplished rapidly to minimize closed-throttle time.

2,250

Mode

2,500

0-25 accel___.

2,750

3,000

3,500

4,000

15-30 accel__

4,500

5,000 5,500

1 Where it is expected that more than 33 percent of the vehicles in an engine displacement class will be equipped with air conditioning, an additional 10 percent will be added to the above listed road load horsepowers for all test vehicles representing such engine class.

(d) Practice cycles should be run to find the correct throttle action to allow completion of the accelerations in the specified time at the constant rates of acceleration specified. Care should be taken to avoid throttle closures in the transition from acceleration to 30 cruise.

(e) The vehicle speed (m.p.h.) as measured from the dynamometer rolls shall be used for all conditions. A speed vs. time recording, as evidence of dynamometer test validity, shall be supplied on request by the Secretary.

§ 85.77 Three-speed manual transmis

sions.

(a) All test conditions except as noted shall be run in highest gear.

(b) Cars equipped with free wheeling or overdrive units shall be tested with this unit (free wheeling or overdrive) locked out of operation.

(c) Idle: Idle shall be run with transmission in gear and with clutch disengaged (except first idle; see § 85.80).

(d) Cruise: The vehicle shall be driven at a constant throttle position to maintain the cruising speed. An engine tachometer and vacuum gauge may be used as driving aids.

(e) Acceleration: Modes shall be run at nearly constant acceleration with the

(f) Deceleration:

Shift speed

1st to 2d gear at

15 m.p.h.

2d to 3d gear at 25

m.p.h.

Use highest gear.

(1) The modes shall be run at closed throttle in high gear with clutch engaged, maintaining a constant deceleration rate by using the vehicle brakes. For those modes which decelerate to zero, the clutch should be depressed when speed drops below 15 m.p.h.

(2) If the vehicle decelerates more rapidly than required with no braking, the decelerations should be made at closed throttle even though less than the specified time is required. Indicate the end of the (30-15 or 20-0) deceleration, continue at that speed until the specified time has elapsed, then proceed with the next sequence.

(g) Optional shift points: When recommended by the manufacturer in the owner's operating manual, second gear may be used in sequences six and seven of § 85.75(a). If this option is utilized, it shall be reported in test results submitted under § 85.51 and a copy of the applicable owner's operating manual shall be submitted with such report.

§ 85.78 Four- and five-speed manual transmissions.

(a) Use the same procedure as threespeed manual transmissions with the following exceptions: